The present invention pertains generally to the field of catheters and, more particularly, to hub or manifold assemblies connected to the proximal end thereof.
Catheters, such as guide catheters, diagnostic catheters and therapeutic catheters, for example, angioplasty and atherectomy catheters generally comprise a flexible tube having a permanently connected hub assembly at one end of the tube. The hub assembly often includes a hub and a strain relief. The hub generally includes a connector for connecting the catheter to a Y-adaptor, inflation device or the like. The strain relief generally extends from the hub along a portion of the catheter tube to provide a transition in flexibility between the hub and the tube.
Prior hub assemblies utilized a two piece construction, for example, the hub was attached to an end of the catheter tube and then the strain relief was attached in a secondary process. The primary reason for the two piece design was the different functions of the hub and strain relief required different materials or material properties. The hub is required to be harder material to withstand forces applied to the connector. The strain relief, however, must provide a stiffness transition from the hub to the catheter shaft. The strain relief material is typically soft and flexible to provide kink-resistance and added support to the catheter shaft proximate the hub.
One such hub assembly is disclosed by Wijkamp et al. in U.S. Pat. No. 5,167,647. In one embodiment, a tubular strain relief is injection molded around one end of the catheter. After the strain relief has hardened, a hub is secured to the strain relief. Alternately, an end of the catheter may be inserted into a hub. The hub and catheter can then be placed into a mold to form the strain relief around the end of the catheter and between the catheter and the hub. Wijkamp et al. also discloses simultaneously molding both the hub and the strain relief from two different materials.
Prichard et al., in U.S. Pat. No. 5,380,301, also disclose a prior hub assembly. Prichard et al. disclose a hub formed of a material having a relatively high durometer hardness in comparison to the catheter. The strain relief is preferably formed of a material having a flexibility and durometer hardness which is greater than that of the catheter, but less than that of the hub. The hub is first separately molded, then an end of the catheter is inserted into the hub. Then both the hub and the portion of the catheter proximal the hub are placed in a mold. As disclosed by Wijkamp et al., the strain relief is then molded around the catheter and between a portion of the hub and the catheter. The hub also includes openings into which molten strain relief material flows to form a mechanical bond between the strain relief and the hub.